Limiter for alternating currents



S. SALTO. LIMITER FOR ALTERNATING CURRENTS.

APPLICATION FILED FEB. 15, I919- Patented Mar. 22, 1921.

um/M30: eLvaToms auro 35 his Elihu W1 UNITED STATES SALVATORE SALTO,

OF MILAN, ITALY.

LIMITER FOR ALTERNATING CURRENTS.

Specification of Letters Patent.

Patented Mar. 22, 1921.

Application filed February 15, 1919. Serial No. 277,235.

T 0 all whom it may concern,

Be it known that I, SALVATORE SALTO, mechanical engineer, a subject of the King of Italy, and residing at Milan, Italy, whose post-ofiice address is 7 Corso Vittorio Emanuele, Milan, Italy, have invented new and useful Improvements in the Limiters for Alternating Currents, of which the following is a specification.

The current limiting apparatus according to the present invention has, in comparlson with known devices, the advantage that it interrupts the current only once when an overload occurs in the distribution system and reestablishes the current automatically as soon as the overload is removed.

The accompanying drawing shows diagrammatically, by way of example, an apparatus constructed according to the present invention.

The current enters the apparatus at the terminal 1 from whence it passes to terminal 4 flows through the winding of an, electromagnet 17 passes to terminal 5, through fixed terminal 6, spring 19, terminal -7--, terminal -3, thence passes to the distribution system, traverses the apparatus 89 inserted in the latter and finally returns to the other terminal 2- of the apparatus. The circuit -l-4-5-67-3- is so designed as to offer a relatively small resistance.

From the point -1 branches off a con ductor leading to the primary winding 11 of a transformer -10-, and then to the point 8-, the resistance of the primary transformer winding being high relatively to the circuit 145673.

One end of the secondary winding -12- of the transformer 10- is connected to the terminal -2- and the other to the end 13 of a second winding of the electro magnet 17--. The other end -14- of this winding is electrically connected to the fulcrum 15 of the magnet armature -18, which is preferably of large surface, and therethrough to the movable contact 16-, which does not contact with the spring 19- except when the armature 18 is attracted by the electromagnet 17.

The apparatus works as follows: When the main current flowing through the magnet coil 4.-5 is in excess of the prede termined value, the armature 18-- is attracted and, by means of contact 16,

depresses the spring 19, thus opening the contact between 6 and -19- and the secondary 12 is energized and a current fiows through 12-1314 -151816 19-7-3-89212-. The electromagnet 17 is now energized by the current fiowingthroughthe coil --l3l4=- and holds the armature 18 until the overload has been removed from the distribution system. On removal of the overload from the secondary or distribution system the current intensity decreases, the armature 18- is released, the spring -19- restablishes contact with the point -16, thus reestablishing the connection of the distribution sys tem with the main system.

The most convenient transformation ratio can be selected so as to obtain the maximum variations in the current intensities for the resistance variations of the distribution system, which bring the load to the proximity of the maximum permissible load.

For adjusting purposes the apparatus is provided with a screw 20-, by means of which the armature 18 can be brought nearer to or away from the electromagnet -17, and the electromagnet is provided with a slot 22 and an iron plate -21, by means of which the resistance of the magnetic circuit of the magnet 17 can be varied in order to adjust the armature release.

The apparatus can be so adjusted that, when an overload occurs in the distribution circuit, the armature 18- is attracted and held up against the magnet poles until the overload is removed, so that no current can ever flow through the distribution system in excess of the current intensity allowed by the limiter.

The apparatus cuts off the current as soon as a short circuit takes place in the system, and restores it again automatically when the short circuit is removed; the apparatus accordingly works as a safety fuse.

The apparatus can also be used for the supply of electricity on the forfeit system for heating purposes, which advantage is not afforded by other limiters. A further advantage is that the apparatus works absolutely automatically, this permitting it to be put out of the reach of the users hands.

In the construction of the apparatus it is, not absolutely indispensable that the armature 18 be attracted by the main current ma netically.

aving fully described my invention, I claim, and desire to secure by Letters Patent:' V

Limiter for alternating current comprising a main circuit, an electromagnet in said circuit, an armaturefor said electromagnet 'acting'as an interrupter for the main cir cuit, a transformer having itsprimary in parallel with the main circuit and its secondary in series with a Winding on the electromagnet forming a circuit branched across the transformer, and when the main circuit is interrupted'by the armature owing to an excess of current passing therethrough, the

current of the circuit of the secondary of the transformer energizes the electromagnet to hold open the main circuit, but the resistance of the primary winding diminishes the current traversing the load circuit.

In testimony whereof I affix my signature this 22 day of January 1919. V

SALVATORE SALTO. 

